Understanding Why Exercise Works for Just About Everything

Centuries ago, the Greek physician Hippocrates noted that when the body is “unused and left idle, it becomes liable to disease, defective in growth, and ages quickly.” These observations—made without the benefit of the exhaustive medical research and detailed studies that we have today—are just as valid now as they were then.

Exercise is a natural medicine available to all. Cardiac research has proven that moderate exercise improves the circulation and metabolism, which reduces the chance of heart attack. Regular exercise also lowers both heart rate and blood pressure, improves the cholesterol profile and helps to prevent the development of life-threatening plaque within the heart’s arteries.

Of course, exercise alone—even if one were to walk more than 100 miles a week—does not grant immunity from life-threatening events such as heart attack and stroke. It can, however, greatly reduce the chances of sudden-death: An exercise study conducted by researchers from the state universities of North Carolina and Washington found that sedentary individuals who devote fewer than 20 minutes a week to vigorous exercise have a 56 times greater risk of dying during their normal activities than do those who exercise for more than 20 minutes daily.

The findings from this study suggest that Americans need to move a lot more: It’s now estimated that 70 percent of Americans are overweight or obese, and approximately 50 percent of adults don’t get enough exercise. Sedentary lifestyle has been directly linked to upwards of 200,000 deaths annually due to coronary artery disease, diabetes, and colon cancer. Some experts now believe that not exercising regularly does as much harm to the body as smoking a pack of cigarettes each day.

Exercising several times a week can be a big step toward improving cardiovascular endurance, muscular strength, muscular endurance, and flexibility—the four basic elements of physical fitness. While each of these elements is essential to overall health, cardiovascular endurance—the ability of the heart, lungs, and circulatory system to do their job—is the most important.

Cardiovascular endurance is built up through exercises or fitness activities that cause the body to deliver increased amounts of oxygen to the exercising muscles. To achieve this, activities must utilize the large muscle groups (such as those in the legs) and, most important, the exercise must be sustained for at least 20 minutes. Importantly, health benefits can be derived from even low-level exercise activities such as walking, hence the “no pain, no gain” paradigm is not the case.

Although fitness has been shown to be among the most potent predictors of future cardiovascular disease, it is one of the only major risk factors that is not routinely assessed by physicians.

Boston researchers are now investigating if specific tests of exercise capacity—and the presence or absence of dozens of molecules in the bloodstream, called metabolites—can be used to identify patients who may benefit from early treatment to prevent cardiovascular disease. The research will also examine how lifestyle, genetic variations, inherited family traits and measurements of heart structure and function match with changes in metabolism during exercise.

This study represents a paradigm shift away from focusing on only resting measurements and a small number of physiologic measurements during exercise in evaluating risk of cardiovascular disease. Instead, the scientists will study breath-by-breath measurements of oxygen uptake as well as a broad array of circulating metabolites during exercise in order to understand metabolic responses to exercise in the population and the ability of exercise response patterns to detect and prevent future cardiovascular disease.

Based on this research, it’s expected within a few years that simple exercise testing equipment will be used in doctors’ offices to assess heart health with a 7-minute test.